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InParanoid: Eukaryotic Ortholog Groups

Collection of pairwise comparisons between 100 whole genomes generated by a fully automatic method for finding orthologs and in-paralogs between TWO species. Ortholog clusters in the InParanoid are seeded with a two-way best pairwise match, after which an algorithm for adding in-paralogs is applied. The method bypasses multiple alignments and phylogenetic trees, which can be slow and error-prone steps in classical ortholog detection. Still, it robustly detects complex orthologous relationships and assigns confidence values for in-paralogs. The original data sets can be downloaded.

URL: http://inparanoid.sbc.su.se/cgi-bin/index.cgi

Resource ID: nif-0000-03024     Resource Type: Resource     Version: Latest Version


protein, ortholog, genome, drosophila pseudoobscura, duplication, entamoeba histolytica, escherichia colik12, eukaryotic, gasterosteus aculeatus, gene, aedes aegypti, apis mellifera, bos taurus, caenorhabditis remanei, candida glabrata, canis familiaris, ciona intestinalis, cryptococcus neoformans, debaromyces hansenii, dictyostelium discoideum, genomic, homolog, inparalog, kluyveromyces lactis, macaca mulatta, monodelphis domestica, orthology, oryza sativa, outparalog, proteome, tetraodon nigroviridis, xenopus tropicalis, blast, proteome, ortholog cluster, cluster, in-paralog, paralog, automatic clustering, genome comparison

Additional Resource Types

Database, Data Analysis Service

Old URLs







Inparanoid eukaryotic ortholog database

Parent Organization

Funding Information

Swedish Research Council, Karolinska Institutet; Stockholm; Sweden, Pfizer Corporation,


Acknowledgement requested


escherichia coli, anopheles gambiae, caenorhabditis briggsae, caenorhabditis elegans, drosophila melanogaster, zebrafish, takifugu rubripes, chicken, human, mouse, chimpanzee, rat, oryza sativa, plasmodium falciparum, arabidopsis thaliana, saccharomyces cerevisiae, schizosaccharomyces pombe, eukaryota

Original Submitter


Version Status


Submitted On

12:00am September 21, 2010

Originated From


Changes from Previous Version

  • Funding Information was changed
  • Additional Resource Types was changed

Version 2

Created 2 weeks ago by Christie Wang

Version 1

Created 5 years ago by Anonymous

InParanoid 6: eukaryotic ortholog clusters with inparalogs.

  • Berglund AC
  • Nucleic Acids Res.
  • 2008 15

The InParanoid eukaryotic ortholog database (http://InParanoid.sbc.su.se/) has been updated to version 6 and is now based on 35 species. We collected all available 'complete' eukaryotic proteomes and Escherichia coli, and calculated ortholog groups for all 595 species pairs using the InParanoid program. This resulted in 2 642 187 pairwise ortholog groups in total. The orthology-based species relations are presented in an orthophylogram. InParanoid clusters contain one or more orthologs from each of the two species. Multiple orthologs in the same species, i.e. inparalogs, result from gene duplications after the species divergence. A new InParanoid website has been developed which is optimized for speed both for users and for updating the system. The XML output format has been improved for efficient processing of the InParanoid ortholog clusters.

Inparanoid: a comprehensive database of eukaryotic orthologs.

  • O'Brien KP
  • Nucleic Acids Res.
  • 2005 1

The Inparanoid eukaryotic ortholog database (http://inparanoid.cgb.ki.se/) is a collection of pairwise ortholog groups between 17 whole genomes; Anopheles gambiae, Caenorhabditis briggsae, Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, Takifugu rubripes, Gallus gallus, Homo sapiens, Mus musculus, Pan troglodytes, Rattus norvegicus, Oryza sativa, Plasmodium falciparum, Arabidopsis thaliana, Escherichia coli, Saccharomyces cerevisiae and Schizosaccharomyces pombe. Complete proteomes for these genomes were derived from Ensembl and UniProt and compared pairwise using Blast, followed by a clustering step using the Inparanoid program. An Inparanoid cluster is seeded by a reciprocally best-matching ortholog pair, around which inparalogs (should they exist) are gathered independently, while outparalogs are excluded. The ortholog clusters can be searched on the website using Ensembl gene/protein or UniProt identifiers, annotation text or by Blast alignment against our protein datasets. The entire dataset can be downloaded, as can the Inparanoid program itself.

InParanoid 7: new algorithms and tools for eukaryotic orthology analysis.

  • Ostlund G
  • Nucleic Acids Res.
  • 2010 22

The InParanoid project gathers proteomes of completely sequenced eukaryotic species plus Escherichia coli and calculates pairwise ortholog relationships among them. The new release 7.0 of the database has grown by an order of magnitude over the previous version and now includes 100 species and their collective 1.3 million proteins organized into 42.7 million pairwise ortholog groups. The InParanoid algorithm itself has been revised and is now both more specific and sensitive. Based on results from our recent benchmarking of low-complexity filters in homology assignment, a two-pass BLAST approach was developed that makes use of high-precision compositional score matrix adjustment, but avoids the alignment truncation that sometimes follows. We have also updated the InParanoid web site (http://InParanoid.sbc.su.se). Several features have been added, the response times have been improved and the site now sports a new, clearer look. As the number of ortholog databases has grown, it has become difficult to compare among these resources due to a lack of standardized source data and incompatible representations of ortholog relationships. To facilitate data exchange and comparisons among ortholog databases, we have developed and are making available two XML schemas: SeqXML for the input sequences and OrthoXML for the output ortholog clusters.

Automatic clustering of orthologs and in-paralogs from pairwise species comparisons.

  • Remm M
  • J. Mol. Biol.
  • 2001 14

Orthologs are genes in different species that originate from a single gene in the last common ancestor of these species. Such genes have often retained identical biological roles in the present-day organisms. It is hence important to identify orthologs for transferring functional information between genes in different organisms with a high degree of reliability. For example, orthologs of human proteins are often functionally characterized in model organisms. Unfortunately, orthology analysis between human and e.g. invertebrates is often complex because of large numbers of paralogs within protein families. Paralogs that predate the species split, which we call out-paralogs, can easily be confused with true orthologs. Paralogs that arose after the species split, which we call in-paralogs, however, are bona fide orthologs by definition. Orthologs and in-paralogs are typically detected with phylogenetic methods, but these are slow and difficult to automate. Automatic clustering methods based on two-way best genome-wide matches on the other hand, have so far not separated in-paralogs from out-paralogs effectively. We present a fully automatic method for finding orthologs and in-paralogs from two species. Ortholog clusters are seeded with a two-way best pairwise match, after which an algorithm for adding in-paralogs is applied. The method bypasses multiple alignments and phylogenetic trees, which can be slow and error-prone steps in classical ortholog detection. Still, it robustly detects complex orthologous relationships and assigns confidence values for both orthologs and in-paralogs. The program, called INPARANOID, was tested on all completely sequenced eukaryotic genomes. To assess the quality of INPARANOID results, ortholog clusters were generated from a dataset of worm and mammalian transmembrane proteins, and were compared to clusters derived by manual tree-based ortholog detection methods. This study led to the identification with a high degree of confidence of over a dozen novel worm-mammalian ortholog assignments that were previously undetected because of shortcomings of phylogenetic methods.A WWW server that allows searching for orthologs between human and several fully sequenced genomes is installed at http://www.cgb.ki.se/inparanoid/. This is the first comprehensive resource with orthologs of all fully sequenced eukaryotic genomes. Programs and tables of orthology assignments are available from the same location.